model <- function(t, state, parms) {
  with(as.list(c(state,parms)), {
    dR <- r*R*(1 - R/k) - d1*R - e*R*N/(h+R)
    dN <- c*e*R*N/(h+R) - d2*N
    return(list(c(dR, dN)))  
  }) 
}  

p <- c(r=0,k=1,h=0,e=0,c=1,d1=0,d2=0)
s <- c(R=0,N=0)